scholarly journals The dispersion characteristics of air pollution from world's megacities

2012 ◽  
Vol 12 (10) ◽  
pp. 26351-26400
Author(s):  
M. Cassiani ◽  
A. Stohl ◽  
S. Eckhardt
Keyword(s):  
Human Population ◽  
Scale Effects ◽  
Lower Troposphere ◽  
Global Scale ◽  
The Arctic ◽  
Particle Model ◽  
Modeling Framework ◽  
Local Conditions ◽  
The Impact ◽  
The City

Abstract. Megacities are extreme examples of the continuously growing urbanization of human population that pose (new) challenges to the environment and human health at a local scale. However, because of their size megacities also have larger-scale effects and more research is needed to quantify their regional and global scale impacts. We performed a study of the characteristics of plumes dispersing from a group of thirty-six of world's megacities using the Lagrangian particle model FLEXPART and focusing on black carbon (BC) emissions during the years 2003–2005. BC was selected since it is representative of combustion-related emissions and it has a significant role as a short-lived climate forcer. Based on the BC emissions two tracers were modeled; a purely passive tracer and one subject to wet and dry deposition. These tracers allowed us to investigate the role of deposition processes in determining the impact of megacities' pollutant plumes. The particles composing the plumes have been sampled in space and time. The time sampling allowed us to investigate the evolution of the plume from its release up to 48 days after emission and to generalize our results for any substance decaying with a time scale sufficiently shorter than the time window of 48 days. The physical characteristics of the time averaged plume have been investigated and this showed that although local conditions are important, overall the latitude of the city is the main factor influencing both the local and the regional-to-global dispersion of the megacities' plumes. We also repeated the calculations of some of the regional-pollution-potential metrics previously proposed by Lawrence et al. (2007), thus extending their results to a depositing scalar and retaining the evolution in time for all the plumes. Noteworthy our results agreed well with the previous results despite being obtained using a totally different modeling framework. For the environmental impact on a global scale we focused on the export of mass from the megacities to the sensitive polar regions. We found that the sole city of Saint Petersburg contributes more to the lower troposphere pollution and deposition in the Arctic than the whole ensemble of Asian megacities. In general this study showed that the pollution of urban origin in the lower troposphere of the Arctic is mainly generated by northern European sources. We also found that the deposition of BC in the Antarctic due to megacities is comparable to the emissions generated by local shipping activities. Finally multiplying population and ground level concentration maps, we found that the exposure of human population to megacities pollution occurs mainly inside the city boundaries and this is especially true if deposition is accounted for. However, some exceptions exist (Beijing, Tianjin, Karachi) where the impact on population outside city boundary is larger than that inside city boundary.

scholarly journals The dispersion characteristics of air pollution from the world's megacities

2013 ◽  
Vol 13 (19) ◽  
pp. 9975-9996 ◽  
Author(s):  
M. Cassiani ◽  
A. Stohl ◽  
S. Eckhardt
Keyword(s):  
Human Population ◽  
Scale Effects ◽  
Lower Troposphere ◽  
Global Scale ◽  
The Arctic ◽  
Particle Model ◽  
Modeling Framework ◽  
Local Conditions ◽  
The Impact ◽  
The City

Abstract. Megacities are extreme examples of the continuously growing urbanization of the human population that pose (new) challenges to the environment and human health at a local scale. However, because of their size megacities also have larger-scale effects, and more research is needed to quantify their regional- and global-scale impacts. We performed a study of the characteristics of pollution plumes dispersing from a group of 36 of the world's megacities using the Lagrangian particle model FLEXPART and focusing on black carbon (BC) emissions during the years 2003–2005. BC was selected since it is representative of combustion-related emissions and has a significant role as a short-lived climate forcer. Based on the BC emissions two artificial tracers were modeled: a purely passive tracer and one subject to wet and dry deposition more closely resembling the behavior of a true aerosol. These tracers allowed us to investigate the role of deposition processes in determining the impact of megacities' pollutant plumes. The particles composing the plumes have been sampled in space and time. The time sampling allowed us to investigate the evolution of the plume from its release up to 48 days after emission and to generalize our results for any substance decaying with a timescale sufficiently shorter than the time window of 48 days. The physical characteristics of the time-averaged plume have been investigated, and this showed that, although local conditions are important, overall a city's latitude is the main factor influencing both the local and the regional-to-global dispersion of its pollution. We also repeated the calculations of some of the regional-pollution-potential metrics previously proposed by Lawrence et al. (2007), thus extending their results to a depositing scalar and retaining the evolution in time for all the plumes. Our results agreed well with their previous results despite being obtained using a totally different modeling framework. For the environmental impact on a global scale we focused on the export of mass from the megacities to the sensitive polar regions. We found that the sole city of Saint Petersburg contributes more to the lower-troposphere pollution and deposition in the Arctic than the whole ensemble of Asian megacities. In general this study showed that the pollution of urban origin in the lower troposphere of the Arctic is mainly generated by northern European sources. We also found that the deposition of the modeled artificial BC aerosol in the Antarctic due to megacities is comparable to the emissions of BC generated by local shipping activities. Finally multiplying population and ground level concentration maps, we found that the exposure of human population to megacity pollution occurs mainly inside the city boundaries, and this is especially true if deposition is accounted for. However, some exceptions exist (Beijing, Tianjin, Karachi) where the impact on population outside the city boundary is larger than that inside the city boundary.

scholarly journals Interannual Variability and Trends in Sea Surface Temperature, Lower and Middle Atmosphere Temperature at Different Latitudes for 1980–2019

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 454
Author(s):  
Andrew R. Jakovlev ◽  
Sergei P. Smyshlyaev ◽  
Vener Y. Galin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Lower Troposphere ◽  
Reanalysis Data ◽  
Sea Surface ◽  
The Arctic ◽  
The Impact

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.

scholarly journals Building Stability On Permafrost In Vorkuta, Russia

2019 ◽  
Author(s):  
P. I. Kotov ◽  
V. Z. Khilimonyuk
Keyword(s):  
Climate Change ◽  
Housing Stock ◽  
Residential Buildings ◽  
Open Data ◽  
Urban Environments ◽  
The Arctic ◽  
Residential Housing ◽  
Infrastructure Stability ◽  
The Impact ◽  
The City

The Infrastructure stability on permafrost is currently an important topic as the Arctic countries are developing climate change adaptation and mitigation programs. Assessing the sustainability of infrastructure facilities (especially in urban environments) is a difficult task as it depends on many parameters. This article discusses the city of Vorkuta, which is located in the northwest of Russia. This city differs from many others built on permafrost because most of buildings were built according to Principle II (The Active Method) of construction on permafrost with thawing soil prior to construction. Assessments of the engineering and geocryological conditions, basic principles of construction in the city, and reasons for building failures, were carried out within this study. The research is based on publications, open data about buildings, and visual observations in Vorkuta. About 800 buildings are in use in Vorkuta in 2020 (43% of what it was 50 years ago). According to the analysis, about 800 houses have been demolished or disconnected from utility lines over the past 50 years (about 250 of these are still standing, pending demolition). Since 1994, the construction of new residential buildings has almost stopped. Therefore, buildings that have been in use for over 50 years will account for 90% of the total residential housing stock by 2040. The effects of climate change in the city will depend primarily on the principle of construction employed and on the geocryological conditions of the district. Buildings constructed according to Principle I (The Passive Method) were found to be more vulnerable due to a decrease in permafrost bearing capacity. The impact of increasing air temperature on some of the buildings built on bedrock (the central part of the city) and some built on thawing soil will be minimal, as other factors are more significant.

scholarly journals Impact of human population density on fire frequency at the global scale

2013 ◽  
Vol 10 (10) ◽  
pp. 15735-15778 ◽  
Author(s):  
W. Knorr ◽  
T. Kaminski ◽  
A. Arneth ◽  
U. Weber
Keyword(s):  
Population Density ◽  
Human Population ◽  
Global Analysis ◽  
Global Scale ◽  
Fire Frequency ◽  
System Component ◽  
Burned Area ◽  
Data Set ◽  
In Fire ◽  
The Impact

Abstract. Human impact on wildfires, a major Earth system component, remains poorly understood. While local studies have found more fires close to settlements and roads, assimilated charcoal records and analyses of regional fire patterns from remote-sensing observations point to a decline in fire frequency with increasing human population. Here, we present a global analysis using three multi-year satellite-based burned-area products combined with a parameter estimation and uncertainty analysis with a non-linear model. We show that at the global scale, the impact of increasing population density is mainly to reduce fire frequency. Only for areas with up to 0.1 people per km2, we find that fire frequency increases by 10 to 20% relative to its value at no population. The results are robust against choice of burned-area data set, and indicate that at only very few places on Earth, fire frequency is limited by human ignitions. Applying the results to historical population estimates results in a moderate but accelerating decline of global burned area by around 14% since 1800, with most of the decline since 1950.

scholarly journals Stratospheric impact on the Northern Hemisphere winter and spring ozone interannual variability in the troposphere

2019 ◽  
Author(s):  
Junhua Liu ◽  
Jose M. Rodriguez ◽  
Luke D. Oman ◽  
Anne R. Douglass ◽  
Mark A. Olsen ◽  
...  
Keyword(s):  
North America ◽  
Tropospheric Ozone ◽  
Interannual Variation ◽  
Stratospheric Ozone ◽  
Lower Troposphere ◽  
The Arctic ◽  
Vertical Extent ◽  
Pinatubo Eruption ◽  
Tropospheric O3 ◽  
The Impact

Abstract. In this study we use O3 and stratospheric O3 tracer simulations from the high-resolution Goddard Earth Observing System, Version 5 (GEOS-5) Replay run (MERRA-2 GMI at 0.5° model resolution ~ 50 km) and observations from ozonesondes to investigate the interannual variation and vertical extent of the stratospheric ozone impact on tropospheric ozone. Our work focuses on the winter and spring seasons over North America and Europe. The model reproduces the observed interannual variation of tropospheric O3, except for the Pinatubo period from 1991 to 1995 over the region of North America. Ozonesonde data show a negative ozone anomaly in 1992–1994 following the Pinatubo eruption, with recovery thereafter. The simulated anomaly is only half the magnitude of that observed. Our analysis suggests that the simulated Stratosphere-troposphere exchange (STE) flux deduced from the analysis might be too strong over the North American (50° N–70° N) region after the Mt. Pinatubo eruption in the early 1990s, masking the impact of lower stratospheric O3 concentration on tropospheric O3. European ozonesonde measurements show a similar but weaker O3 depletion after the Mt. Pinatubo eruption, which is fully reproduced by the model. Analysis based on a stratospheric O3 tracer (StratO3) identifies differences in strength and vertical extent of stratospheric ozone influence on the tropospheric ozone interannual variation (IAV) between North America and Europe. Over North America, the StratO3 IAV has a significant impact on tropospheric O3 from the upper to lower troposphere and explains about 60 % and 66 % of simulated O3 IAV at 400 hPa, ~ 11 % and 34 % at 700 hPa in winter and spring respectively. Over Europe, the influence is limited to the middle to upper troposphere, and becomes much smaller at 700 hPa. The stronger and deeper stratospheric contributions in the tropospheric O3 IAV over North America shown by the model is likely related to ozonesondes' being closer to the polar vortex in winter with lower geopotential height, lower tropopause height, and stronger coupling to the Arctic Oscillation in the lower troposphere (LT) than over Europe.

Sub-grid scale representation of halogen chemistry in volcanic plumes based on 1D MOCAGE model simulations

2021 ◽  
Author(s):  
Virginie Marécal ◽  
Ronan Voisin-Pessis ◽  
Tjarda Roberts ◽  
Paul Hamer ◽  
Alessandro Aiuppa ◽  
...  
Keyword(s):  
Transport Model ◽  
Scale Effects ◽  
Regional Scale ◽  
Global Scale ◽  
Horizontal Resolution ◽  
Mt Etna ◽  
Modelling Studies ◽  
1D Model ◽  
High Concentrations ◽  
The Impact

<p>Halogen halides emitted by volcanoes are known to rapidly convert within plumes into BrO while depleting ozone, as clearly shown by observations and models over the past 2 decades (e.g. review by Gutmann et al., 2018). So far, most of the modelling studies have focused on the plume processes occurring in the first few hours after the emission. The only study at the regional scale is that of Jourdain et al. (2016). They assessed the impact of volcanic halogens for a period of strong degassing of the Ambrym volcano, showing in particular its effect on the atmospheric oxidizing capacity and methane lifetime.</p><p>A step further would be to quantify the impact of volcanic halogens at the global scale using global chemistry models. This type of model uses a horizontal resolution (greater than 50 km) that is much coarser than the plume size. This raises the issue of, whether at this resolution, it is possible to represent the chemistry occurring under high concentrations within the plume. To assess this, a sub-grid scale parameterization is proposed. It has been tested in the 1D version of MOCAGE global and regional chemistry transport model for a short eruption of Mt Etna on the 10<sup>th</sup> of May 2008. The results show that while using the subgrid-scale plume parameterization or not does change the timing of when the maximum BrO occurs but does not affect the predicted maximum concentration. The same finding is made when using a range of different settings in the parameterization regarding dilution of the plume with its environment. The 1D model results show a sensitivity of BrO formation to parameters other than the sub-grid scale effects: composition of the plume at the vent, injection height of the emissions, and time of the day when the eruption takes place.</p>

scholarly journals Retrieval of MetOp-A/IASI CO profiles and validation with MOZAIC data

2012 ◽  
Vol 5 (3) ◽  
pp. 3271-3301
Author(s):  
E. De Wachter ◽  
B. Barret ◽  
E. Le Flochmoën ◽  
E. Pavelin ◽  
M. Matricardi ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
Correlation Coefficients ◽  
Global Scale ◽  
Upper Troposphere ◽  
Retrieval Algorithms ◽  
Good Reproduction ◽  
The Impact ◽  
Good Agreement ◽  
Limited Sensitivity

Abstract. The IASI nadir looking thermal infrared sounder onboard MetOp-A enables the monitoring of atmospheric constituents on a global scale. This paper presents a quality assessment of IASI CO profiles retrieved by the two different retrieval algorithms SOFRID and FORLI, by an intercomparison with airborne in-situ CO profiles from the MOZAIC program. A statistical analysis shows a very good agreement between the two retrieval algorithms and smoothed MOZAIC data for the lower troposphere (surface-480 hPa) with correlation coefficients r ~ 0.8, and a good agreement in the upper troposphere (480–225 hPa) with r ~ 0.7. Closer investigation of the temporal variation of the CO profiles at the airports of Frankfurt and Windhoek demonstrates that on the overall a very good agreement is found between the IASI products and smoothed MOZAIC data in terms of seasonal variability. At Frankfurt SOFRID (resp. FORLI) is positively biased by 10.5% (resp. 13.0%) compared to smoothed MOZAIC in the upper (resp. lower) troposphere, and the limited sensitivity of the IASI instrument to the boundary layer when thermal contrast is low is identified. At Windhoek, we find a good reproduction of the impact of the vegetation fires in Southern Africa from July to November by both SOFRID and FORLI, with an overestimation of the CO background values (resp. fire maxima) by SOFRID (resp. FORLI) by 12.8% (resp. ~10%). Profile comparisons at Frankfurt and Windhoek identify a reduced performance of the nighttime retrievals of both products compared to daytime retrievals.

scholarly journals Life cycle assessment of single-use and reusable plastic bottles in the city of Johannesburg

2021 ◽  
Vol 117 (11/12) ◽  
Author(s):  
Kunle I. Olatayo ◽  
Paul T. Mativenga
Keyword(s):  
South Africa ◽  
Life Cycle ◽  
Dominant Factor ◽  
Impact Categories ◽  
Local Conditions ◽  
Pet Bottles ◽  
Single Use ◽  
Life Cycle Impact ◽  
The Impact ◽  
The City

Polyethylene terephthalate (PET) bottles of water have experienced huge growth in demand and sales in South Africa. This expansion in use creates challenges as well as opportunities for managing the life cycle impact. The properties that make PET desirable for fluid-containing bottles have also made it highly resistant to environmental biodegradation. Reusable plastic bottles are now marketed as a solution to reduce the impact of single-use plastic bottles. We assessed the life cycle impact of single-use PET bottles and an alternative, reusable PET bottle based on consumption patterns in South Africa and the material flow and supply chain in the urban environment. This robust consideration of local conditions is important in evaluating the life cycle impact. In an examination of 13 impact categories, the reusable PET bottle had lower impact than the single-use bottle in all the impact categories examined. The mass of PET bottle material required to deliver the water needs at any given time is a dominant factor on the environmental burden. Extending the life of reusable bottles and designing lighter weight bottles would reduce their life cycle impact. Information obtained in evaluating alternatives to plastic water bottles can be valuable for providing a foundation assessment for policymakers and plastic bottle manufacturers to make informed choices and to focus on improvements in life cycle impact.

SPECIFIC TOURIST AND RECREATION OFFERS OF AN AMERICAN COASTAL CITY – ON THE EXAMPLE OF HUNTINGTON BEACH (USA, SOUTH CALIFORNIA)

2019 ◽  
Vol 51 ◽  
pp. 59-76
Author(s):  
Janusz Olearnik
Keyword(s):  
Sustainable Use ◽  
Local Conditions ◽  
Tourist Attractions ◽  
Direct Observations ◽  
Coastal Cities ◽  
Seaside Resort ◽  
The Impact ◽  
Active Leisure ◽  
The City

Purpose. Recognition of specifics regarding the tourist offer at a renowned seaside resort in Southern California and indication as to which of these specific features of the offer could be used in developing tourist offers in Poland. Method. The basic method used is case study, that is the tourist aspect of the city of Huntington Beach. The research material for the creation of this study was mainly collected using the method of direct observation, including participation during an internship in 2018 and annual visits from 2011 to 2016, as well as the study of printed and Internet materials. Findings. The main identified characteristics of the analysed offer are: sustainable use of natural and infrastructural conditions for tourism, suitably varied level of conditions for stay - adaptation to tourist segments, active leisure opportunities based on perfect use of local conditions, care for a clear tourist image of the city and specific local colour, mega-events, the impact of numerous tourist attractions in nearby towns. Research and conclusions limitations. Research was based on direct observations covering a specific case of one city. It is used to look for patterns for other tourist centres. Practical implications. It was indicated how the specific properties of the Huntington Beach tourist offer could be used to improve tourist offers in Polish coastal cities. Originality. The originality of the article consists in presenting and evaluating the tourist offer of Huntington Beach, a popular and renowned recreation centre in California. The source of originality concerns expert observations collected and systematised as a result of repeated stays in this city. Type of paper. The article can be considered as a case study.

scholarly journals The effect of horizontal gradients and spatial measurement resolution on the retrieval of global vertical NO<sub>2</sub> distributions from SCIAMACHY measurements in limb only mode

2010 ◽  
Vol 3 (4) ◽  
pp. 1155-1174 ◽  
Author(s):  
J. Puķīte ◽  
S. Kühl ◽  
T. Deutschmann ◽  
S. Dörner ◽  
P. Jöckel ◽  
...  
Keyword(s):  
Trace Gases ◽  
Polar Vortex ◽  
Global Scale ◽  
The Arctic ◽  
Horizontal Gradient ◽  
Horizontal Distance ◽  
Operational Mode ◽  
Transport Barrier ◽  
Horizontal Gradients ◽  
The Impact

Abstract. Limb measurements provided by the Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale. Combining measurements of the same air volume from different viewing positions along the orbit, a tomographic approach can be applied and 2-D distribution fields of stratospheric trace gases can be acquired in one inversion. With this approach, it is possible to improve the accounting for the effect of horizontal gradients in the trace gas distribution on the profile retrieval. This was shown in a previous study for the retrieval of NO2 and OClO profiles in the Arctic region near the polar vortex boundary. In this study, the tomographic retrieval is applied on measurements during special limb-only orbits performed on 14 December 2008. For these orbits the distance between consecutive limb scanning sequences was reduced to ~3.3° of the orbital circle (i.e. more than two times with respect to the nominal operational mode). Thus, the same air volumes are scanned successively by more than one scanning sequence also for midlatitudes and the tropics. It is found that the profiles obtained by the tomographic 2-D approach show significant differences to those obtained by the 1-D approach. In particular, for regions close to stratospheric transport barriers (i.e. near to the edge of the polar vortex and subtropical transport barrier) up to 50% larger or smaller NO2 number densities (depending on the sign of the gradient along the line of sight) for altitudes below the peak of the profile (around 20 km) are obtained. The limb-only measurements allow examining the systematic error if the horizontal gradient is not accounted for, and studying the impact of the gradient strength on the profile retrieval on a global scale. The findings for the actual SCIAMACHY observations are verified by sensitivity studies for simulated data for which the NO2 distributions to be retrieved are known in advance. In addition, the impact of the horizontal distance between consecutive limb scanning sequences on the quality of the tomographic 2-D retrieval is investigated and a possibility to take into account the horizontal gradients by an interpolation approach is studied.

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